Floor plate for a cooling freight

ABSTRACT

A floor plate for a cooling container of sandwich construction in which an upper cover plate and a lower cover plate are bridged by a rigid foam. The gooseneck tunnel of the floor plate is insulated by a vacuum insulated plate which can contain a support medium and which is embedded in the surrounding foam.

FIELD OF THE INVENTION

[0001] The present invention relates to a floor plate for a cooling container of a sandwich construction and provided with cooling passages formed by a T grating (a grating composed of T-section members) which is closed by an upper cover plate and wherein a rigid foam is provided as an insulation between the upper and lower cover plates.

BACKGROUND OF THE INVENTION

[0002] Floor structures for containers which are provided with cooling passages are described, for example, in DE 44 33 728A and DE 597 02 926.

[0003] Such floor structures are widely used in cooling containers which are used to ship freight which must be cooled or at least prevented from excess heating. They are largely successful because they can take substantial loads and have excellent insulating properties. The insulation is primarily the rigid foam mentioned previously.

[0004] However, rigid insulating foams must comply with environmental standards, especially with respect to the use of fluorinated-chlorinated hydrocarbons. Since rigid foams have been developed, the use of fluorinated-chlorinated hydrocarbons as foaming agents for polyurethanes have been banned and products which contain such foams are increasingly being eliminated from commerce the use of fluorinated-chlorinated hydrocarbons containing foaming agents has the additional drawback that the foams which are produced are more limited in effectiveness than more recently developed commercial foams. The increased thickness which is required for the less efficient foams results in a reduction of the container volume and cooling containers with the prior foams for that disadvantage.

[0005] An especially critical point with respect to the insulation is the so-called gooseneck tunnel in which the insulating layer can only have about {fraction (1/5)} of the main layer thickness for the remaining regions of the floor plate. The insulating action of the foam utilized in this region is an order of magnitude less than what is generally deemed to be necessary and hence effective insulation in the gooseneck tunnel region is a significant problem.

OBJECT OF THE INVENTION

[0006] It is, therefore, the principal object of the present invention to provide a floor plate for a cooling container, especially of the type in which the floor plate is provided with passages is a cooling medium, in which the gooseneck tunnel has substantially the same insulating effect as other regions of the floor plate.

[0007] Another object of the invention is to improve the insulating effectiveness of floor plates for cooling containers so that the aforementioned drawback is avoided.

SUMMARY OF THE INVENTION

[0008] These objects and others which will be apparent hereinafter are attained, in accordance with the invention by providing the region of the gooseneck tunnel as a vacuum insulated plate.

[0009] By providing one or more vacuum insulated plates if the insulation of the floor of the cooling container, at least in the region of the gooseneck tunnel, is significantly lower thermal transfer characteristics of the vacuum insulated plate, by comparison with rigid foams, can be utilized to increase the insulating character of the gooseneck tunnel structure so that, in the region of the gooseneck tunnel, the insulation effect is at least equal to that of the floor plate elsewhere. The vacuum maintained in the plate or plates delimiting the gooseneck tunnel, of course, accounts for the enhanced insulating effect.

[0010] As a consequence, despite the significantly reduced layer thickness of the insulation in the gooseneck tunnel region an insulating effect can be obtained which is equivalent to the full insulating effect elsewhere on the floor plate even in the critical region of the gooseneck tunnel.

BRIEF DESCRIPTION OF THE DRAWING

[0011] The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

[0012]FIG. 1 is a cross sectional view through a floor plate in the region of the gooseneck tunnel;

[0013]FIG. 2 is a perspective view of a vacuum insulated plate which is utilized in the floor plate of FIG. 1;

[0014]FIG. 3 is a partial section through the vacuum insulated plate; and

[0015]FIGS. 4 and 5 are cross sectional views similar to FIG. 3 showing alternative support media for the vacuum insulated plate.

SPECIFIC DESCRIPTION

[0016] The floor plate 1 shown in FIG. 1 has a sandwich construction and is provided with passages two through which cooling air is forced as defined by a T grating 3, namely, a grating composed of T-cross section bars. The switch structure has an upper cover plate 4 and a lower cover plate 5 between which a rigid insulating foam 6 is provided. In the region of the gooseneck tunnel 7, however, the insulation for the floor plate 1 is provided by a vacuum insulated plate 8. This vacuum insulated plate 8 can span the entire region of the gooseneck tunnel 7. It is fixed on the lower cover plate 5 and can extend into and be embedded in the adjoining rigid foam 6, i.e. foamed therein.

[0017] The vacuum insulated plate 8 can be composed of a rectangular box structure 9 (FIG. 2) which is sealed around its edges and has an interior 10 in which a vacuum is sustained. The interior may also contain a packaging medium to support the broad walls defining the interior 10. The packing 11, which is porous and can provide sufficient interstitial spaces for the vacuum to remain effective, can be composed of a low thermal conductivity material like diatamaceous earth as shown at 11. The packing material prevents collapse of the vacuum insulated plate by the prevalent atmospheric pressure acting on all sides thereof and affords mechanical strength to the vacuum insulated plate. The support medium 11 can alternatively, be rock wall, a plastic grid or some other structure of low thermal conductivity, capable of supporting the walls without comprising the ability to evacuate the plate. The walls of the plate can be composed of metal, e.g. stainless steel or some other material impermeable to gases.

[0018]FIG. 4 shows an alternative in which the support structure 12 for the vacuum insulated plate 8 is rock wool. FIG. 5 shows a support structure consisting of a plastic grid 13 as the support structure for a vacuum insulated plate. 

I claim:
 1. A floor plate for a cooling container comprising: a sandwich structure formed by an upper cover plate, a lower cover plate and a rigid insulating foam between said cover plates; a T-section grating forming passages for cooling air; and a gooseneck tunnel formed in said floor plate and insulated by a vacuum insulated plate.
 2. The floor plate for the cooling container as defined in claim 1 wherein the vacuum insulated plate is fixed to the lower cover plate.
 3. The floor plate for the cooling container as defined in claim 2 wherein the vacuum insulated plate is embedded in the rigid foam.
 4. The floor plate for the cooling container as defined in claim 3 wherein the vacuum insulated plate is embedded by foaming the rigid foam around edges of the vacuum insulated plate.
 5. The floor plate for the cooling container as defined in claim 3 wherein the vacuum insulated plate is composed of a flat rectangular box structure in an interior of which a vacuum is maintained.
 6. The floor plate for the cooling container as defined in claim 5, further comprising a support medium within said box structure.
 7. The floor plate for the cooling container as defined in claim 6 wherein the support medium is composed of diatomaceous earth.
 8. The floor plate for the cooling container as defined in claim 6 wherein the support medium is composed of rock wool.
 9. The floor plate for the cooling container as defined in claim 6 wherein the support medium is composed of plastic grid. 